PCSK9 immunization using nanoliposomes: preventive efficacy against hypercholesterolemia and atherosclerosis

Silencing hepatic PCSK9 via novel chimeric AAV8 mitigates the progression of atherosclerosis by inhibiting inflammation in ApoE-/- mice

Adeno-associated virus (AAV) is the most widely utilized vector for gene therapy. Proprotein convertase subtilisin/kexin type 9 (PCSK9), predominantly expressed in the liver, plays a crucial role in lipid regulation and atherosclerosis progression. Here, we developed a novel chimeric AAV8.P-PCSK9 short hairpin RNA (shRNA) vector that incorporates a cross-species specific shRNA targeting PCSK9 to assess its effects on lipid levels and atherosclerosis in mice. AAV8.P demonstrated superior transduction efficiency and safety, achieving about 90% liver transduction and maintaining transgene expression for up to a year. The AAV8.P-PCSK9 shRNA exhibited typical liver-tropism and effectively silenced hepatic PCSK9. Moreover, it significantly lowered serum cholesterol and triglyceride levels while increasing LDL-R level without causing hepatotoxicity in wild-type mice. Additionally, it decreased PCSK9 expression and elevated low-density lipoprotein receptor expression in Apolipoprotein E-deficient mice, leading to early changes in lipid profiles but lacking a sustained impact on circulating lipids. Importantly, silencing PCSK9 resulted in reduced plaque areas with enhanced stability, decreased inflammatory macrophage infiltration, and lower levels of vascular and systemic inflammatory markers. These findings indicate that targeted silencing of hepatic PCSK9 significantly reduces lipid levels and effectively mitigates atherosclerosis progression by inhibiting inflammatory responses via the AAV8.P-PCSK9 shRNA vector, thereby providing critical support for its clinical translation.

Evaluating the effect of the antiPCSK9 vaccine on systemic inflammation and oxidative stress in an experimental mouse model

BACKGROUND

To investigate whether the antiPCSK9 vaccine can affect the CRP and oxidative stress (OS) during acute systemic inflammation.

METHODS

Male albino mice were randomly divided into three groups: non-treated mice (the sham group), treated with a nonspecific stimulator of the immune response - Freund's complete adjuvant (CFA; the CFA group), and vaccinated mice treated with CFA (the vaccine group). The vaccine group was subcutaneously immunized with the antiPCSK9 formulation, 4 × in bi-weekly intervals. To induce inflammation, all mice were subjected to the CFA challenge after the vaccination plan. The hsCRP level and OS status were evaluated by a mouse CRP ELISA kit and the pro-oxidant antioxidant balance (PAB) assay, respectively.

RESULTS

The vaccine induced a high-titter IgG antiPCSK9 antibody, which was accompanied with a significant PCSK9 reduction (-24.7% and -28.5% compared with the sham and CFA group, respectively), and the inhibition of PCSK9/LDLR interaction (-27.8% and -29.4%, respectively). hsCRP was significantly increased in the vaccine and CFA groups by 225% and 274% respectively, when compared with the sham group; however, it was non-significantly decreased (-18%; p = 0.520) in the vaccine group in comparison with the CFA group. The PAB values indicated that OS was significantly increased in the CFA group (by 72.7%) and the vaccine group (by 76%) when compared to the sham group; however, there was no significant difference in the PAB values between the vaccine and CFA groups.

CONCLUSION

The antiPCSK9 vaccine failed to significantly reduce the serum hs-CRP and OS induced in the CFA-challenged albino mice.

Vaccination as a Promising Approach in Cardiovascular Risk Mitigation: Are We Ready to Embrace a Vaccine Strategy?

Cardiovascular disease (CVD) remains a leading global health concern, with atherosclerosis being its principal cause. Standard CVD treatments primarily focus on mitigating cardiovascular (CV) risk factors through lifestyle changes and cholesterol-lowering therapies. As atherosclerosis is marked by chronic arterial inflammation, the innate and adaptive immune systems play vital roles in its progression, either exacerbating or alleviating disease development. This intricate interplay positions the immune system as a compelling therapeutic target. Consequently, immunomodulatory strategies have gained increasing attention, though none have yet reached widespread clinical adoption. Safety concerns, particularly the suppression of host immune defenses, remain a significant barrier to the clinical application of anti-inflammatory therapies. Recent decades have revealed the significant role of adaptive immune responses to plaque-associated autoantigens in atherogenesis, opening new perspectives for targeted immunological interventions. Preclinical models indicate that vaccines targeting specific atherosclerosis-related autoantigens can slow disease progression while preserving systemic immune function. In this context, numerous experimental studies have advanced the understanding of vaccine development by exploring diverse targeting pathways. Key strategies include passive immunization using naturally occurring immunoglobulin G (IgG) antibodies and active immunization targeting low-density lipoprotein cholesterol (LDL-C) and apolipoproteins, such as apolipoprotein B100 (ApoB100) and apolipoprotein CIII (ApoCIII). Other approaches involve vaccine formulations aimed at proteins that regulate lipoprotein metabolism, including proprotein convertase subtilisin/kexin type 9 (PCSK9), cholesteryl ester transfer protein (CETP), and angiopoietin-like protein 3 (ANGPTL3). Furthermore, the literature highlights the potential for developing non-lipid-related vaccines, with key targets including heat shock proteins (HSPs), interleukins (ILs), angiotensin III (Ang III), and a disintegrin and metalloproteinase with thrombospondin motifs 7 (ADAMTS-7). However, translating these promising findings into safe and effective clinical therapies presents substantial challenges. This review provides a critical evaluation of current anti-atherosclerotic vaccination strategies, examines their proposed mechanisms of action, and discusses key challenges that need to be overcome to enable clinical translation.

Recent advances of self-assembled nanoparticles in the diagnosis and treatment of atherosclerosis

Atherosclerosis remains a significant global health challenge, with its related conditions as the leading cause of death, underscoring the urgent need for enhanced diagnostic and therapeutic approaches. Recently, self-assembled nanoparticles (SANPs) have shown remarkable promise in treating atherosclerosis, attributed to their superior bioavailability, biodegradability, biocompatibility, and ease of functional modification. Numerous SANP variants, such as DNA origami, metal-organic frameworks (MOFs), nanozymes, peptide-based nanoparticles, and self-assembled prodrug nanoparticles, have been engineered, extending their utility in targeted drug delivery and imaging. Advances in fabrication technologies, including microfluidic techniques, allow for precise and scalable SANP production, while innovative nanoparticle designs-such as stimuli-responsive and carrier-free variants-enhance pharmacokinetic properties. The deployment of SANPs in atherosclerosis has introduced a range of diagnostic and therapeutic solutions, from non-invasive imaging and stimuli-responsive drug delivery to vaccination, theranostics, and biosensing. This review consolidates the recent progress in SANP applications for atherosclerosis, emphasizing their transformative potential in disease management.

Research progress on the therapeutic effects of nanoparticles loaded with drugs against atherosclerosis

Presently, there are many drugs for the treatment of atherosclerosis (AS), among which lipid-lowering, anti-inflammatory, and antiproliferative drugs have been the most studied. These drugs have been shown to have inhibitory effects on the development of AS. Nanoparticles are suitable for AS treatment research due to their fine-tunable and modifiable properties. Compared with drug monotherapy, experimental results have proven that the effects of nanoparticle-encapsulated drugs are significantly enhanced. In addition to nanoparticles containing a single drug, there have been many studies on collaborative drug treatment, collaborative physical treatment (ultrasound, near-infrared lasers, and external magnetic field), and the integration of diagnosis and treatment. This review provides an introduction to the therapeutic effects of nanoparticles loaded with drugs to treat AS and summarizes their advantages, including increased targeting ability, sustained drug release, improved bioavailability, reduced toxicity, and inhibition of plaque and vascular stenosis.

Transforming hypercholesterolemia management: Spotlight on PCSK9 peptide vaccines

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a therapeutic target for dyslipidemia and atherosclerotic cardiovascular disease (ASCVD). Two recent studies published by Fang et al.1 and Zhang et al.2 in Cell Reports Medicine and Cell Reports, respectively, show the efficacy of peptide vaccines in eliciting an antibody response against PCSK9 and reducing plasma cholesterol levels.

Development of a PCSK9-targeted nanoparticle vaccine to effectively decrease the hypercholesterolemia

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the low-density lipoprotein receptor (LDLR) and mediates its internalization and degradation, resulting in an increase in LDL cholesterol levels. Recently, PCSK9 emerged as a therapeutic target for hypercholesterolemia and atherosclerosis. In this study, we develop a PCSK9 nanoparticle (NP) vaccine by covalently conjugating the catalytic domain (aa 153-aa 454, D374Y) of PCSK9 to self-assembled 24-mer ferritin NPs. We demonstrate that the PCSK9 NP vaccine effectively induces interfering antibodies against PCSK9 and reduces serum lipids levels in both a high-fat diet-induced hypercholesterolemia model and an adeno-associated virus-hPCSK9D374Y-induced hypercholesterolemia model. Additionally, the vaccine significantly reduces plaque lesion areas in the aorta and macrophages infiltration in an atherosclerosis mouse model. Furthermore, we discover that the vaccine's efficacy relied on T follicular help cells and LDLR. Overall, these findings suggest that the PCSK9 NP vaccine holds promise as an effective treatment for hypercholesterolemia and atherosclerosis.

Role of Treg cell subsets in cardiovascular disease pathogenesis and potential therapeutic targets

In the genesis and progression of cardiovascular diseases involving both innate and adaptive immune responses, inflammation plays a pivotal and dual role. Studies in experimental animals indicate that certain immune responses are protective, while others exacerbate the disease. T-helper (Th) 1 cell immune responses are recognized as key drivers of inflammatory progression in cardiovascular diseases. Consequently, the CD4+CD25+FOXP3+ regulatory T cells (Tregs) are gaining increasing attention for their roles in inflammation and immune regulation. Given the critical role of Tregs in maintaining immune-inflammatory balance and homeostasis, abnormalities in their generation or function might lead to aberrant immune responses, thereby initiating pathological changes. Numerous preclinical studies and clinical trials have unveiled the central role of Tregs in cardiovascular diseases, such as atherosclerosis. Here, we review the roles and mechanisms of Treg subsets in cardiovascular conditions like atherosclerosis, hypertension, myocardial infarction and remodeling, myocarditis, dilated cardiomyopathy, and heart failure. While the precise molecular mechanisms of Tregs in cardiac protection remain elusive, therapeutic strategies targeting Tregs present a promising new direction for the prevention and treatment of cardiovascular diseases.

Whether and Why Do We Need a Vaccine Against Atherosclerosis? Can We Expect It Anytime Soon?

PURPOSE OF REVIEW

Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of premature death. Lipid disorders, particularly elevated serum low-density lipoprotein cholesterol (LDL-C), contribute significantly to ASCVD. The risk of developing ASCVD is influenced by the duration of exposure to elevated LDL-C concentrations (cholesterol-years concept). Implementing lipid-lowering treatments based on the principles of "the earlier the better," "the lower the better," and "the longer the better" has been shown to reduce cardiovascular risk and significantly extend lifespan. Despite the availability of numerous lipid-lowering drugs, achieving satisfactory control of lipid disorders remains very challenging. Therefore, there is a need for novel approaches to improve treatment adherence.

RECENT FINDINGS

One promising solution under investigation is the development of an anti-PCSK9 vaccine, which could be administered annually to provide long-term control over LDL-C concentrations. Experimental studies and the sole clinical trial conducted thus far have demonstrated that the anti-PCSK9 vaccine induces a durable immune response associated with lipid-lowering and anti-atherosclerotic effects. Furthermore, it has exhibited good tolerability and a satisfactory safety profile. However, we still need data from phase 2, 3, and cardiovascular outcome trial to confirm its safety and efficacy and add value in the armamentarium of available and perspective lipid-lowering drugs. This article highlights the significance of developing an anti-PCSK9 vaccine and provides an overview of the current knowledge on various anti-PCSK9 vaccines.

Optimization of the MACE endpoint composition to increase power in studies of lipid-lowering therapies-a model-based meta-analysis

Aims

To develop a model-informed methodology for the optimization of the Major Adverse Cardiac Events (MACE) composite endpoint, based on a model-based meta-analysis across anti-hypercholesterolemia trials of statin and anti-PCSK9 drugs.

Methods and results

Mixed-effects meta-regression modeling of stand-alone MACE outcomes was performed, with therapy type, population demographics, baseline and change over time in lipid biomarkers as predictors. Randomized clinical trials up to June 28, 2022, of either statins or anti-PCSK9 therapies were identified through a systematic review process in PubMed and ClinicalTrials.gov databases. In total, 54 studies (270,471 patients) were collected, reporting 15 different single cardiovascular events. Treatment-mediated decrease in low density lipoprotein cholesterol, baseline levels of remnant and high-density lipoprotein cholesterol as well as non-lipid population characteristics and type of therapy were identified as significant covariates for 10 of the 15 outcomes. The required sample size per composite 3- and 4-point MACE endpoint was calculated based on the estimated treatment effects in a population and frequencies of the incorporated events in the control group, trial duration, and uncertainty in model parameters.

Conclusion

A quantitative tool was developed and used to benchmark different compositions of 3- and 4-point MACE for statins and anti-PCSK9 therapies, based on the minimum population size required to achieve statistical significance in relative risk reduction, following meta-regression modeling of the single MACE components. The approach we developed may be applied towards the optimization of the design of future trials in dyslipidemia disorders as well as in other therapeutic areas.

Targeting PCSK9 to tackle cardiovascular disease

Lowering blood cholesterol levels efficiently reduces the risk of developing atherosclerotic cardiovascular disease (ASCVD), including coronary artery disease (CAD), which is the main cause of death worldwide. CAD is caused by plaque formation, comprising cholesterol deposits in the coronary arteries. Proprotein convertase subtilisin kexin/type 9 (PCSK9) was discovered in the early 2000s and later identified as a key regulator of cholesterol metabolism. PCSK9 induces lysosomal degradation of the low-density lipoprotein (LDL) receptor in the liver, which is responsible for clearing LDL-cholesterol (LDL-C) from the circulation. Accordingly, gain-of-function PCSK9 mutations are causative of familial hypercholesterolemia, a severe condition with extremely high plasma cholesterol levels and increased ASCVD risk, whereas loss-of-function PCSK9 mutations are associated with very low LDL-C levels and protection against CAD. Since the discovery of PCSK9, extensive investigations in developing PCSK9 targeting therapies have been performed. The combined delineation of clear biology, genetic risk variants, and PCSK9 crystal structures have been major drivers in developing antagonistic molecules. Today, two antibody-based PCSK9 inhibitors have successfully progressed to clinical application and shown to be effective in reducing cholesterol levels and mitigating the risk of ASCVD events, including myocardial infarction, stroke, and death, without any major adverse effects. A third siRNA-based inhibitor has been FDA-approved but awaits cardiovascular outcome data. In this review, we outline the PCSK9 biology, focusing on the structure and nonsynonymous mutations reported in the PCSK9 gene and elaborate on PCSK9-lowering strategies under development. Finally, we discuss future perspectives with PCSK9 inhibition in other severe disorders beyond cardiovascular disease.

Targeting PCSK9 and Beyond for the Management of Low-Density Lipoprotein Cholesterol

Reducing low-density lipoprotein cholesterol (LDL-C) levels is crucial to the prevention of atherosclerotic cardiovascular disease (ASCVD). However, many patients, especially those at very high ASCVD risk or with familial hypercholesterolemia (FH), do not achieve target LDL-C levels with statin monotherapy. The underutilization of novel lipid-lowering therapies (LLT) globally may be due to cost concerns or therapeutic inertia. Emerging approaches have the potential to lower LDL-C and reduce ASCVD risk further, in addition to offering alternatives for statin-intolerant patients. Shifting the treatment paradigm towards initial combination therapy and utilizing novel LLT strategies can complement existing treatments. This review discusses innovative approaches including combination therapies involving statins and agents like ezetimibe, bempedoic acid, cholesterol ester transfer protein (CETP) inhibitors as well as strategies targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) and angiopoietin-like protein 3 (ANGPTL3) inhibition. Advances in nucleic acid-based therapies and gene editing are innovative approaches that will improve patient compliance and adherence. These strategies demonstrate significant LDL-C reductions and improved cardiovascular outcomes, offering potential for optimal LDL-C control and reduced ASCVD risk. By addressing the limitations of statin monotherapy, these approaches provide new management options for elevated LDL-C levels.

Identification of Potent Small-Molecule PCSK9 Inhibitors Based on Quantitative Structure-Activity Relationship, Pharmacophore Modeling, and Molecular Docking Procedure

The leading cause of atherosclerotic cardiovascular disease (ASCVD) is elevated low-density lipoprotein cholesterol (LDL-C). Proprotein convertase subtilisin/kexin type 9 (PCSK9) attaches to the domain of LDL receptor (LDLR), diminishing LDL-C influx and LDLR cell surface presentation in hepatocytes, resulting in higher circulating LDL-C levels. PCSK9 dysfunction has been linked to lower levels of plasma LDLC and a decreased risk of coronary heart disease (CHD). Herein, using virtual screening tools, we aimed to identify a potent small-molecule PCSK9 inhibitor in compounds that are currently being studied in clinical trials. We first performed chemical absorption, distribution, metabolism, excretion, and toxicity (ADMET) filtering of 9800 clinical trial compounds obtained from the ZINC 15 database using Lipinski's rule of 5 and achieved 3853 compounds. Two-dimensional (2D) quantitative structure-activity relationship (QSAR) was initiated by computing molecular descriptors and selecting important descriptors of 23 PCSK9 inhibitors. Multivariate calibration was performed with the partial least square regression (PLS) method with 18 compounds for training to design the QSAR model and 5 compounds for the test set to assess the model. The best latent variables (LV) (LV=6) with the lowest value of Root-Mean-Square Error of Cross-Validation (RMSECV) of 0.48 and leave-one-out cross-validation correlation coefficient (R2CV) = 0.83 were obtained for the QSAR model. The low RMSEC (0.21) with high R²cal (0.966) indicates the probability of fit between the experimental data and the calibration model. Using QSAR analysis of 3853 compounds, 2635 had a pIC50<1 and were considered for pharmacophore screening. The PHASE module (a complete package for pharmacophore modeling) designed the pharmacophore hypothesis through multiple ligands. The top 14 compounds (pIC50>1) were defined as active, whereas 9 (pIC50<1) were considered as an inactive set. Three five-point pharmacophore hypotheses achieved the highest score: DHHRR1, DHHRR2, and DHRRR1. The highest and best model with survival scores (5.365) was DHHRR1, comprising 1 hydrogen donor (D), 2 hydrophobic groups (H), and 2 rings of aromatic (R) features. We selected the molecules with a higher 1.5 fitness score (257 compounds) in pharmacophore screening (DHHRR1) for molecular docking screening. Molecular docking indicates that ZINC000051951669, with a binding affinity: of -13.2 kcal/mol and 2 H-bonds, has the highest binding to the PCSK9 protein. ZINC000011726230 with energy binding: -11.4 kcal/mol and 3 H-bonds, ZINC000068248147 with binding affinity: -10.7 kcal/mol and 1 H-bond, ZINC000029134440 with a binding affinity: -10.6 kcal/mol and 4 H-bonds were ranked next, respectively. To conclude, the archived molecules identified as inhibitory PCSK9 candidates, and especially ZINC000051951669 may therefore significantly inhibit PCSK9 and should be considered in the newly designed trials.

Two decades of vaccine development against atherosclerosis

Atherosclerosis is an immune-mediated chronic inflammatory disease that leads to the development of fatty plaques in the arterial walls, ultimately increasing the risk of thrombosis, stroke, and myocardial infarction. The immune response in this complex disease is both atheroprotective and pro-atherogenic, involving both innate and adaptive immunity. Current treatments include the adjustment of lifestyle factors, cholesterol-lowering drugs such as statins, and immunotherapy, whereas vaccine development has received comparatively little attention. In this review, we discuss the potential of antigen-specific vaccination as a preventative approach based on more than 20 years of research and innovation. Vaccination targets include proteins that are more abundant in atherosclerotic patients, such as oxidized low-density lipoprotein (LDL), apolipoprotein B-100, proprotein convertase subtilisin/kexin type-9 serine protease (PCSK9), cholesteryl ester transfer protein (CETP), and heat shock proteins HSP60 and HSP65. Immunization with such proteins or their peptide epitopes has been shown to induce T-cell activation, produce antigen-specific antibodies, reduce the size of atherosclerotic lesions, and/or reduce serum cholesterol levels. Vaccination against atherosclerosis therefore offers a new strategy to address the burden on healthcare systems caused by cardiovascular disease, the leading cause of death worldwide.

Low cholesterol states: clinical implications and management

INTRODUCTION

Hypocholesterolemia results from genetic - both monogenic and polygenic - and non-genetic causes and can sometimes be a source of clinical concern. We review etiologies and sequelae of hypocholesterolemia and therapeutics inspired from genetic hypocholesterolemia.

AREAS COVERED

Monogenic hypocholesterolemia disorders caused by the complete absence of apolipoprotein (apo) B-containing lipoproteins (abetalipoproteinemia and homozygous hypobetalipoproteinemia) or an isolated absence of apo B-48 lipoproteinemia (chylomicron retention disease) lead to clinical sequelae. These include gastrointestinal disturbances and severe vitamin deficiencies that affect multiple body systems, i.e. neurological, musculoskeletal, ophthalmological, and hematological. Monogenic hypocholesterolemia disorders with reduced but not absent levels of apo B lipoproteins have a milder clinical presentation and patients are protected against atherosclerotic cardiovascular disease. Patients with heterozygous hypobetalipoproteinemia have somewhat increased risk of hepatic disease, while patients with PCSK9 deficiency, ANGPTL3 deficiency, and polygenic hypocholesterolemia typically have anunremarkable clinical presentation.

EXPERT OPINION

In patients with severe monogenic hypocholesterolemia, early initiation of high-dose vitamin therapy and a low-fat diet are essential for optimal prognosis. The molecular basis of monogenic hypocholesterolemia has inspired novel therapeutics to help patients with the opposite phenotype - i.e. elevated apo B-containing lipoproteins. In particular, inhibitors of PCSK9 and ANGPTL3 show important clinical impact.

Preclinical toxicity assessment of a peptide-based antiPCSK9 vaccine in healthy mice

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition is a novel cholesterol-lowering treatment for decreasing the risk of atherosclerosis. We have previously shown that active immunization using the antiPCSK9 vaccine could decrease hypercholesterolemia and impede the development of atherosclerotic lesions in the experimental model of atherosclerosis. Here, we evaluated the toxicity of the vaccine in healthy mice.

METHODS

Forty male and female albino mice were divided into 4 experimental groups, including vaccine female (10 mice) and male (10 mice) groups receiving the antiPCSK9 vaccine as well as the corresponding control female (10 mice) and male (10 mice) groups receiving the phosphate buffer. Vaccination was planned based on 4 subcutaneous injections of the vaccine formulation (10 µg/mouse) in bi-weekly intervals. The toxicity study was performed by the subacute protocol, 28 days after the last vaccine injection. To this end, the plasma levels of lipid indexes, urea, creatinine, AST, ALT, ALP, and fasting plasma glucose (FPG), as well as the CBC test were measured. To evaluate histopathological alterations, various tissues including the heart, liver, kidney, spleen, and brain were studied using hematoxylin & eosin (H&E) staining by an expert pathologist. The severity of damage to the tissue was considered based on the standard classification; grade 1 as light damage, grade 2 as moderate damage, grade 3 as near intense damage, and grade 4 as intense damage.

RESULTS

The results showed non-significant changes of total cholesterol, LDL-C, triglyceride, HDL-C, FBS, creatinine, urea, AST, ALP, ALT, and PAB in the vaccinated mice when compared with control mice. The CBS test indicated that there were no significant changes in the levels of WBC, RBC, HGB, HCT, MCH, MCHC, PLT, LYM, NEUT, MCV, RDW-S, PDW, and MPV in the vaccinated mice when compared with control mice. Evaluating histopathological alterations in various tissues indicated no significant adverse effects in vaccinated mice when compared to control mice.

CONCLUSION

The findings of the present study indicate that antiPCSK9 is safe and exerts no adverse effects on the function of different organs and blood levels of cellular and biochemical biomarkers in healthy mice.

PCSK9 Inhibitors Have Apolipoprotein C-III-Related Anti-Inflammatory Activity, Assessed by 1H-NMR Glycoprotein Profile in Subjects at High or very High Cardiovascular Risk

Atherosclerosis is a chronic inflammatory disease caused by the accumulation of cholesterol in the intima. Proprotein convertase subtilisin/kexin type 9 inhibitors (iPCSK9) can reduce low-density lipoprotein (LDL) cholesterol levels by 60%, but there is still no evidence that they can lower markers of systemic inflammation such as high-sensitivity C-reactive protein (hsCRP). Acute-phase serum glycoproteins are upregulated in the liver during systemic inflammation, and their role as inflammatory biomarkers is under clinical evaluation. In this observational study, we evaluate the effects of iPCSK9 on glycoproteins (Glyc) A, B and F. Thirty-nine patients eligible for iPCSK9 therapy were enrolled. One sample before and after one to six months of iPCSK9 therapy with alirocumab was obtained from each patient. Lipids, apolipoproteins, hsCRP and PCSK9 levels were measured by biochemical analyses, and the lipoprotein and glycoprotein profiles were measured by 1H nuclear magnetic resonance (1H-NMR). The PCSK9 inhibitor reduced total (36.27%, p < 0.001), LDL (55.05%, p < 0.001) and non-high-density lipoprotein (HDL) (45.11%, p < 0.001) cholesterol, apolipoprotein (apo) C-III (10%, p < 0.001), triglycerides (9.92%, p < 0.001) and glycoprotein signals GlycA (11.97%, p < 0.001), GlycB (3.83%, p = 0.017) and GlycF (7.26%, p < 0.001). It also increased apoA-I (2.05%, p = 0.043) and HDL cholesterol levels (11.58%, p < 0.001). Circulating PCSK9 levels increased six-fold (626.28%, p < 0.001). The decrease in Glyc signals positively correlated with the decrease in triglycerides and apoC-III. In conclusion, in addition to LDL cholesterol, iPCSK9 therapy also induces a reduction in systemic inflammation measured by 1H-NMR glycoprotein signals, which correlates with a decrease in triglycerides and apoC-III.

The effect of PCSK9 immunization on the hepatic level of microRNAs associated with the PCSK9/LDLR pathway

INTRODUCTION

MicroRNAs (miRNAs) are a class of gene expression epigenetic regulators that play roles in regulating genes involved in cholesterol homeostasis, including low-density lipoprotein receptor (LDLR) and PCSK9; therefore, miRNAs have been suggested as potential therapeutic targets for treating cardiometabolic disorders. Thus, the present study aimed to assess the effect of immunotherapy with the PCSK9 peptide vaccine on the hepatic expression levels of microRNAs associated with the LDLR pathway, including miRNA-27a, miRNA-30c, and miRNA-191, in normal vaccinated mice.

MATERIAL AND METHODS

PCSK9 immunogenic peptide and 0.4% alum adjuvant were mixed at a 1 : 1 ratio and used as a vaccine formulation. Male albino mice were randomly assigned to the vaccine or control group. Mice in the vaccine group were injected four times at two-week intervals with a PCSK9 peptide vaccine, and mice in the control group were injected with phosphate-buffered saline (PBS). Animal livers were sampled 2 weeks after the last injection to assess miRNA expression levels. The hepatic expression levels of miRNA-27a, miRNA-30c, and miRNA-191 were evaluated by SYBR Green real-time PCR, quantified by a comparative (2- Δ Δ CT) method (fold change (FC)) and normalized to U6 small nuclear RNA (U6snRNA) expression as an internal control.

RESULTS

The hepatic expression level of miRNA-27a was significantly lower in mice following immunotherapy with the PCSK9 peptide vaccine compared to the control group (FC: 0.731 ±0.1, p = 0.027). Also, there was a borderline significantly lower hepatic expression level of miRNA-30c in the vaccinated group compared to the control (FC: 0.569 ±0.1, p = 0.078). However, no significant differences were found in the hepatic expression level of miRNA-191 between the two studied groups (FC: 0.852 ±0.1, p = 0.343).

CONCLUSIONS

According to the findings, the PCSK9 peptide vaccine could effectively reduce the hepatic expression level of miRNA-27a and may be helpful in the management of LDL-C level and atherosclerosis, which may be mediated through the LDLR pathway.

Coffee or tea: Anti-inflammatory properties in the context of atherosclerotic cardiovascular disease prevention

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of premature death worldwide. Inflammation and its biomarkers, like C-reactive protein (CRP), among the risk factors, such as hypertension, lipid disorders, and diabetes, may be also responsible for the residual cardiovascular disease (CVD) risk. Modern lipid-lowering treatment with statins, ezetimibe, PCSK9 inhibitors, or bempedoic acid does not fully protect against inflammation. The recommendations of the International Lipid Expert Panel (ILEP) indicate selected nutraceuticals with anti-inflammatory properties. Diet may have a significant impact on inflammation. Especially interesting in the context of inflammation is the consumption of coffee and tea. These drinks in many observational studies significantly reduced cardiovascular risk and mortality. The question is whether the anti-inflammatory effects of these drinks contribute significantly to the observed clinical effects. Thus, in this narrative review, we primarily discuss the anti-inflammatory properties of consuming tea and coffee. Based on a comprehensive analysis of the studies and their meta-analyses, inconsistent results were obtained, which makes it impossible to conclusively state how clinically significant the potential anti-inflammatory properties of black and green tea and coffee are. A number of confounding factors can cause the inconsistency of the available results. Consumption of tea and coffee appears to increase adiponectin concentrations, decrease reactive oxygen species, decrease low density lipoprotein (LDL) cholesterol concentrations (effect of green tea, etc.). Despite the still uncertain anti-inflammatory effect of tea and coffee, we recommend their consumption as a part of the healthy diet.

Evinacumab, an ANGPTL3 Inhibitor, in the Treatment of Dyslipidemia

Familial hypercholesterolemia (FH) is an inherited disorder. The level of low-density lipoprotein cholesterol (LDL-C) in patients with homozygous FH can be twice as high as that in patients with heterozygous FH. The inhibition of ANGPTL3 shows an important therapeutic approach in reducing LDL-C and triglycerides (TG) levels and, thus, is a potentially effective strategy in the treatment of FH. Evinacumab is a monoclonal antibody inhibiting circulating ANGPTL3, available under the trade name Evkeeza^® for the treatment of homozygous FH. It was reported that evinacumab is effective and safe in patients with homozygous and heterozygous FH, as well as resistant hypercholesterolemia and hypertriglyceridemia. This paper summarizes existing knowledge on the role of ANGPTL3, 4, and 8 proteins in lipoprotein metabolism, the findings from clinical trials with evinacumab, a fully human ANGPTL3 mAb, and the place for this new agent in lipid-lowering therapy.

PCSK9 in Liver Cancers at the Crossroads between Lipid Metabolism and Immunity

Metabolic rewiring and defective immune responses are considered to be the main driving forces sustaining cell growth and oncogenesis in many cancers. The atypical enzyme, proprotein convertase subtilisin/kexin type 9 (PCSK9), is produced by the liver in large amounts and plays a major role in lipid metabolism via the control of the low density lipoprotein receptor (LDLR) and other cell surface receptors. In this context, many clinical studies have clearly demonstrated the high efficacy of PCSK9 inhibitors in treating hyperlipidemia and cardiovascular diseases. Recent data implicated PCSK9 in the degradation of major histocompatibility complex I (MHC-I) receptors and the immune system as well as in other physiological activities. This review highlights the complex crosstalk between PCSK9, lipid metabolism and immunosuppression and underlines the latest advances in understanding the involvement of this convertase in other critical functions. We present a comprehensive assessment of the different strategies targeting PCSK9 and show how these approaches could be extended to future therapeutic options to treat cancers with a main focus on the liver.

Functions and therapeutic interventions of non-coding RNAs associated with TLR signaling pathway in atherosclerosis

Nowadays, emerging data demonstrate that the toll-like receptor (TLR) signaling pathway plays an important role in the progression of inflammatory atherosclerosis. Indeed, dysregulated TLR signaling pathway could be a cornerstone of inflammation and atherosclerosis, which contributes to the development of cardiovascular diseases. It is interesting to note that this pathway is heavily controlled by several mechanisms, such as epigenetic factors in which the role of non-coding RNAs (ncRNAs), particularly microRNAs and long noncoding RNAs as well as circular RNAs in the pathogenesis of atherosclerosis has been well studied. Recent years have seen a significant surge in the amount of research exploring the interplay between ncRNAs and TLR signaling pathway downstream targets in the development of atherosclerosis; however, there is still considerable room for improvement in this field. The current study was designed to review underlying mechanisms of TLR signaling pathway and ncRNA interactions to shed light on therapeutic implications in patients with atherosclerosis.

Serum PCSK9 is positively correlated with disease activity and Th17 cells, while its short-term decline during treatment reflects desirable outcomes in ankylosing spondylitis patients

OBJECTIVE

Proprotein convertase subtilisin/kexin type 9 (PCSK9) participates in the autoimmune disease pathology by regulating T helper (Th) cell differentiation, NF-κB pathway, toll-like receptor 4, etc. This study intended to investigate the association of serum PCSK9 with disease activity, Th cells, and treatment response in ankylosing spondylitis (AS) patients.

METHODS

Eighty-nine active AS patients were enrolled in this multicenter, prospective study. Serum was collected from AS patients at week (W)0, W4, W8, and W12, as well as from 20 osteoarthritis patients and 20 healthy controls after enrollment to detect PCSK9 by ELISA. Based on the ASAS40 response at W12, AS patients were classified as responders and non-responders.

RESULTS

PCSK9 was increased in AS patients versus healthy controls (P < 0.001) and osteoarthritis patients (P = 0.006). In AS patients, PCSK9 was positively linked with C-reactive protein (CRP) (P = 0.003) and ASDAS-CRP (P = 0.017), but not with other clinical properties (P > 0.05). Besides, PCSK9 was negatively correlated with interleukin-4 (P = 0.034), positively associated with Th17 cells (P = 0.005) and interleukin-17A (P = 0.014), but did not relate to Th1 cells, interferon-γ, or Th2 cells (all P > 0.05). Additionally, PCSK9 was decreased from W0 to W12 in general AS patients (P < 0.001) and responders (P < 0.001) but remained unchanged in non-responders (P = 0.129). Moreover, PCSK9 was lower at W4 (P = 0.045), W8 (P = 0.008), and W12 (P = 0.004) in responders versus non-responders. Furthermore, the treatment options did not affect the PCSK9 level (P > 0.05).

CONCLUSION

Serum PCSK9 is positively associated with disease activity and Th17 cells, while its short-term decline reflects desirable treatment response in AS patients.

The role of PCSK9 in NAFLD/NASH and therapeutic implications of PCSK9 inhibition

INTRODUCTION

There are inconsistent findings regarding the effect of lipid-lowering agents on nonalcoholic fatty liver disease (NAFLD). Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) is an important player in cholesterol homeostasis and intracellular lipogenesis, and PCSK9 inhibitors (PCSK9-i) have been found to be efficient for pharmacological management of hyperlipidemia.

AREAS COVERED

Whether PCSK9 (itself) or PCSK9-i affects NAFLD is still disputed. To address this question, we review published preclinical and clinical studies providing evidence for the role of PCSK9 in and the effect of PCSK9-I on the development and pathogenesis of NAFLD.

EXPERT OPINION

The current evidence from a landscape of preclinical and clinical studies examining the role of PCSK9 in NAFLD shows controversial results. Preclinical studies indicate that PCSK9 associates with NAFLD and nonalcoholic steatohepatitis (NASH) progression in opposite directions. In humans, it has been concluded that the severity of hepatic steatosis affects the correlation between circulating PCSK9 and liver fat content in humans, with a possible impact of circulating PCSK9 in the early stages of NAFLD, but not in the late stages. However, data from clinical trials with PCSK9-i reassure to the safety of these agents, although real-life long-term evidence is needed.

PCSK9 Inhibition: From Current Advances to Evolving Future

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine protease synthesized primarily by the liver. It mainly promotes the degradation of low-density lipoprotein receptor (LDL-R) by binding LDL-R, reducing low-density lipoprotein cholesterol (LDL-C) clearance. In addition to regulating LDL-R, PCSK9 inhibitors can also bind Toll-like receptors (TLRs), scavenger receptor B (SR-B/CD36), low-density lipoprotein receptor-related protein 1 (LRP1), apolipoprotein E receptor-2 (ApoER2) and very-low-density lipoprotein receptor (VLDL-R) reducing the lipoprotein concentration and slowing thrombosis. In addition to cardiovascular diseases, PCSK9 is also used in pancreatic cancer, sepsis, and Parkinson’s disease. Currently marketed PCSK9 inhibitors include alirocumab, evolocumab, and inclisiran, as well as small molecules, nucleic acid drugs, and vaccines under development. This review systematically summarized the application, preclinical studies, safety, mechanism of action, and latest research progress of PCSK9 inhibitors, aiming to provide ideas for the drug research and development and the clinical application of PCSK9 in cardiovascular diseases and expand its application in other diseases.

Reactive Oxygen Species Scavenging Nanomedicine for the Treatment of Ischemic Heart Disease

Ischemic heart disease (IHD) is the leading cause of disability and mortality worldwide. Reactive oxygen species (ROS) have been shown to play key roles in the progression of diabetes, hypertension, and hypercholesterolemia, which are independent risk factors that lead to atherosclerosis and the development of IHD. Engineered biomaterial-based nanomedicines are under extensive investigation and exploration, serving as smart and multifunctional nanocarriers for synergistic therapeutic effect. Capitalizing on cell/molecule-targeting drug delivery, nanomedicines present enhanced specificity and safety with favorable pharmacokinetics and pharmacodynamics. Herein, the roles of ROS in both IHD and its risk factors are discussed, highlighting cardiovascular medications that have antioxidant properties, and summarizing the advantages, properties, and recent achievements of nanomedicines that have ROS scavenging capacity for the treatment of diabetes, hypertension, hypercholesterolemia, atherosclerosis, ischemia/reperfusion, and myocardial infarction. Finally, the current challenges of nanomedicines for ROS-scavenging treatment of IHD and possible future directions are discussed from a clinical perspective.

Impact of bariatric surgery on circulating PCSK9 levels as a marker of cardiovascular disease risk: a meta-analysis

INTRODUCTION

This systematic review and meta-analysis focuses on PCSK9 changes in obese patients following bariatric surgery.

METHODS

A systematic literature search in four databases was performed. Comprehensive Meta-Analysis (CMA) V2 software used to conduct the meta-analysis. Studies were evaluated regarding heterogeneity in design, populations under investigation, and treatment duration using a random-effects model and the generic inverse variance weighting approach. A random-effect meta-regression approach was used to investigate the association with the estimated effect size.

RESULTS

The results of the meta-analysis on 4 trials including 260 individuals demonstrated a remarkable decline of PCSK9 after bariatric surgery (WMD = -57.34 ng/ml, 95% CI: -87.97, -26.71, p < 0.001; I 2 = 96.25%). Consistently, a significant decrease of LDL-C after bariatric surgery (WMD = -22.57 mg/dl, 95% CI: -27.5, -17.574, p < 0.001; I 2 = 86.35%) was observed.

CONCLUSIONS

PCSK9 is reduced significantly after bariatric surgery. The decrease of PCSK9 might be utilized as an independent surrogate marker of improvement of atherosclerotic cardiovascular disease risk after bariatric surgery.

Chasing LDL cholesterol to the bottom - PCSK9 in perspective

Low-density lipoprotein (LDL) indubitably contributes causally to atherosclerosis, a leading challenge to health worldwide. Interventions that lower LDL cholesterol (LDL-C) have made remarkable inroads against this global scourge. Recent therapeutic advances have achieved ever lower levels of LDL-C. Improved cardiovascular outcomes continue to accrue from these interventions. In particular, the discovery of the role of proprotein convertase subtilisin/kexin type 9 (PCSK9) as the causal gene in autosomal-dominant hypercholesterolemia has led with remarkable speed to the development of novel agents to lower LDL-C concentrations beyond prior measures, and to alleviate further cardiovascular risk. We review how this story, and its position in the broader landscape of therapy to prevent atherosclerotic events, represents a notable victory of contemporary cardiovascular medicine and reflects successful partnerships between basic scientists, the pharmaceutical and biotechnology sectors, and clinical investigators. Continued cooperation in this manner promises to yield further progress in combating cardiovascular diseases beyond interventions on LDL-C.

Lipid-Modifying Therapies and Stroke Prevention

PURPOSE OF REVIEW

We reviewed lipid-modifying therapies and the risk of stroke and other cerebrovascular outcomes, with a focus on newer therapies.

RECENT FINDINGS

Statins and ezetimibe reduce ischemic stroke risk without increasing hemorrhagic stroke risk. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors similarly reduce ischemic stroke risk in statin-treated patients with atherosclerosis without increasing hemorrhagic stroke, even with very low achieved low-density lipoprotein cholesterol levels. Icosapent ethyl reduces the risk of total and first ischemic stroke in patients with established cardiovascular disease or diabetes mellitus. Clinical outcome trials are underway for newer lipid-modifying agents, including inclisiran, bempedoic acid, and pemafibrate. New biologic agents including evinacumab, pelacarsen, olpasiran, and SLN360 are also discussed. In addition to statins and ezetimibe, PCSK9 inhibitors and icosapent ethyl reduce the risk of ischemic stroke without increasing the risk of hemorrhagic stroke. These therapies dramatically expand options for reducing stroke in high-risk settings.

Targeted Strategy in Lipid-Lowering Therapy

Dyslipidemia is characterized by a diminished lipid profile, including increased level of total cholesterol and low-density lipoprotein cholesterol (LDL-c) and reduced level of high-density lipoprotein cholesterol (HDL-c). Lipid-lowering agents represent an efficient tool for the prevention or reduction of progression of atherosclerosis, coronary heart diseases and metabolic syndrome. Statins, ezetimibe, and recently proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are the most effective and used drugs in clinical lipid-lowering therapy. These drugs are mainly aimed to lower cholesterol levels by different mechanisms of actions. Statins, the agents of the first-line therapy-known as 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors-suppress the liver cholesterol synthesis. Ezetimibe as the second-line therapy can decrease cholesterol by inhibiting cholesterol absorption. Finally, the PCSK9 inhibitors act as an inducer of LDL excretion. In spite of their beneficial lipid-lowering properties, many patients suffer from their serious side effects, route of administration, or unsatisfactory physicochemical characteristics. Clinical demand for dose reduction and the improvement of bioavailability as well as pharmacodynamic and pharmacokinetic profile has resulted in the development of a new targeted therapy that includes nanoparticle carriers, emulsions or vaccination often associated with another more subtle form of administration. Targeted therapy aims to exert a more potent drug profile with lipid-lowering properties either alone or in mutual combination to potentiate their beneficial effects. This review describes the most effective lipid-lowering drugs, their favorable and adverse effects, as well as targeted therapy and alternative treatments to help reduce or prevent atherosclerotic processes and cardiovascular events.

Inflammation and atherosclerosis: signaling pathways and therapeutic intervention

Atherosclerosis is a chronic inflammatory vascular disease driven by traditional and nontraditional risk factors. Genome-wide association combined with clonal lineage tracing and clinical trials have demonstrated that innate and adaptive immune responses can promote or quell atherosclerosis. Several signaling pathways, that are associated with the inflammatory response, have been implicated within atherosclerosis such as NLRP3 inflammasome, toll-like receptors, proprotein convertase subtilisin/kexin type 9, Notch and Wnt signaling pathways, which are of importance for atherosclerosis development and regression. Targeting inflammatory pathways, especially the NLRP3 inflammasome pathway and its regulated inflammatory cytokine interleukin-1β, could represent an attractive new route for the treatment of atherosclerotic diseases. Herein, we summarize the knowledge on cellular participants and key inflammatory signaling pathways in atherosclerosis, and discuss the preclinical studies targeting these key pathways for atherosclerosis, the clinical trials that are going to target some of these processes, and the effects of quelling inflammation and atherosclerosis in the clinic.

Harnessing Intranasal Delivery Systems of Sumatriptan for the Treatment of Migraine

Sumatriptan (ST) is a commonly prescribed drug for treating migraine. The efficiency of several routes of ST administration has been investigated. Recently, the intranasal route with different delivery systems has gained interest owing to its fast-acting and effectiveness. The present study is aimed at reviewing the available studies on novel delivery systems for intranasal ST administration. The oral route of ST administration is common but complicated with some problems. Gastroparesis in patients with migraine may reduce the absorption and effectiveness of ST upon oral use. Furthermore, the gastrointestinal (GI) system and hepatic metabolism can alter the pharmacokinetics and clinical effects of ST. The bioavailability of conventional nasal liquids is low due to the deposition of a large fraction of the delivered dose of a drug in the nasal cavity. Several delivery systems have been utilized in a wide range of preclinical and clinical studies to enhance the bioavailability of ST. The beneficial effects of the dry nasal powder of ST (AVP-825) have been proven in clinical studies. Moreover, other delivery systems based on microemulsions, microspheres, and nanoparticles have been introduced, and their higher bioavailability and efficacy were demonstrated in preclinical studies. Based on the extant findings, harnessing novel delivery systems can improve the bioavailability of ST and enhance its effectiveness against migraine attacks. However, further clinical studies are needed to approve the safety and efficacy of employing such systems in humans.

CRISPR Gene Editing in Lipid Disorders and Atherosclerosis: Mechanisms and Opportunities

Elevated circulating concentrations of low-density lipoprotein cholesterol (LDL-C) have been conclusively demonstrated in epidemiological and intervention studies to be causally associated with the development of atherosclerotic cardiovascular disease. Enormous advances in LDL-C reduction have been achieved through the use of statins, and in recent years, through drugs targeting proprotein convertase subtilisin/kexin type 9 (PCSK9), a key regulator of the hepatic LDL-receptor. Existing approaches to PCSK9 targeting have used monoclonal antibodies or RNA interference. Although these approaches do not require daily dosing, as statins do, repeated subcutaneous injections are nevertheless necessary to maintain effectiveness over time. Recent experimental studies suggest that clustered regularly interspaced short palindromic repeats (CRISPR) gene-editing targeted at PCSK9 may represent a promising tool to achieve the elusive goal of a 'fire and forget' lifelong approach to LDL-C reduction. This paper will provide an overview of CRISPR technology, with a particular focus on recent studies with relevance to its potential use in atherosclerotic cardiovascular disease.

PCSK9 inhibition-based therapeutic approaches: an immunotherapy perspective

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors (PCSK9-I) are novel therapeutic tools to decrease cardiovascular risk. These agents work by lowering the low-density lipoprotein cholesterol (LDL-C) in hypercholesterolemic patients who are statin resistant/intolerant. Current clinically approved and investigational PCSK9-I act generally by blocking PCSK9 activity in the plasma or suppressing its expression or secretion by hepatocytes. The most widely investigated method is the disruption of PCSK9/LDL receptor (LDLR) interaction by fully-humanized monoclonal antibodies (mAbs), evolocumab and alirocumab, which have been approved for the therapy of hypercholesterolemia and atherosclerotic cardiovascular disease (CVD). Besides, a small interfering RNA called inclisiran, which specifically suppresses PCSK9 expression in hepatocytes, is as effective as mAbs but with administration twice a year. Because of the high costs of such therapeutic approaches, several other PCSK9-I have been surveyed, including peptide-based anti-PCSK9 vaccines and small oral anti-PCSK9 molecules, which are under investigation in preclinical and phase I clinical studies. Interestingly, anti-PCSK9 vaccination has been found to serve as a more widely feasible and more cost-effective therapeutic tool over mAb PCSK9-I for managing hypercholesterolemia. The present review will discuss LDL-lowering and cardioprotective effects of PCSK9-I, mainly immunotherapy-based inhibitors including mAbs and vaccines, in preclinical and clinical studies.

Impact of PCSK9 Immunization on Glycemic Indices in Diabetic Rats

METHODS

To prepare the anti-PCSK9 vaccine, a peptide construct called Immunogenic Fused PCSK9-Tetanus (IFPT) was linked to the surface of nanoliposome carriers. Healthy rats received four subcutaneous injections of the vaccine at biweekly intervals. Two weeks after the last vaccination, anti-PCSK9 antibody titers, PCSK9 targeting, and inhibition of PCSK9-low-density lipoprotein receptor (LDLR) interaction were evaluated. After verification of antibody generation, the immunized rats were intraperitoneally treated with a single dose (45 mg/kg) of streptozotocin (STZ) to induce diabetes mellitus. The levels of fasting blood glucose (FBG) were measured, and the oral glucose tolerance test (OGTT) as well as the insulin tolerance test (ITT) were carried out to assess glycemic status. At the end of the study, the total cholesterol, low-density lipoprotein cholesterol (LDL-C), triglyceride, and high-density lipoprotein cholesterol concentrations were assayed. Histopathology examination of the liver and pancreas was also performed using the hematoxylin-eosin staining method.

RESULTS

The prepared nanoliposomal vaccine could strongly induce anti-PCSK9 antibodies in the vaccinated rats. Within one week following the STZ injection, the FBG level was lower in the vaccinated group vs. diabetic control group (49% (-171.7 ± 35 mg/dL, p < 0.001)). In the OGTT, the injected rats showed improved glucose tolerance as reflected by the reduction of blood glucose levels over 180 min, compared with the diabetic controls. Moreover, the ITT demonstrated that, after the insulin injection, blood glucose concentration declined by 49.3% in the vaccinated group vs. diabetic control group. Expectedly, the vaccinated rats exhibited lower (-26.65%, p = 0.03) plasma LDL-C levels compared with the diabetic controls. Histopathology examination of pancreas tissue demonstrated that the pancreatic islets of the vaccinated rats had a slight decline in the population of β-cells and few α-cells. Normal liver histology was also observed in the vaccinated rats.

CONCLUSION

PCSK9 inhibition through the liposomal IFPT vaccine can improve the glucose and insulin tolerance impairments as well as the lipid profile in diabetes.

Pre-Clinical Evaluation of the Nanoliposomal antiPCSK9 Vaccine in Healthy Non-Human Primates

BACKGROUND

Our previous studies showed the safe preventive and therapeutic effects of immunization using the nanoliposomal antiPCSK9 vaccine called "Liposomal Immunogenic Fused PCSK9-Tetanus plus Alum adjuvant" (L-IFPTA), in mouse models of atherosclerosis. Here we aimed to ascertain the immunogenicity and safety of the L-IFPTA vaccine in a pre-clinical study in healthy non-human primates.

METHODS

Five male rhesus macaque monkeys were subcutaneously immunized with the L-IFPTA vaccine, four times with bi-weekly intervals. To evaluate immunogenicity, the plasma antiPCSK9 antibody in immunized monkeys was detected and quantified using the ELISA method. The functionality of the induced antiPCSK9 antibodies was determined by the PCSK9/LDLR in vitro binding assay kit. The safety of the vaccine was tested using the evaluation of several major circulating indicators including plasma lipid alterations, inflammatory biomarkers and organ injury biomarkers.

RESULTS

The resultant data indicated that the L-IFPTA vaccine significantly and highly induced the generation of functional and safe antiPCSK9 antibodies in immunized monkeys. Plasma levels of specific biomarkers indicating organ performance including creatinine, urea, uric acid, bilirubin, ALP, AS, ALT and TSH were not significantly altered. After immunization in healthy monkeys, non-prespecified endpoints (plasma levels of TC, LDL-C, VLDL-C and TG) were non-significantly reduced by 11.6 ± 36%; 16 ± 28%; 22 ± 53% and 24 ± 51%, respectively, while HDL-C was slightly increased by 2 ± 64%. There were also no significant changes in plasma levels of pro- and anti-inflammatory biomarkers.

CONCLUSION

The L-IFPTA vaccine could efficiently stimulate the host humoral immune response to produce active antibodies that inhibit plasma PCSK9 while not provoking systemic inflammation and not adversely affecting organ performance.